The present invention relates to an airbag for protecting a passenger in an emergency, such as a car crash, and more specifically, relates to an airbag suitable for a driver-side airbag installed in a steering device.
In a driver-side airbag apparatus, an airbag folded and housed in a retainer has been widely used, and a cover member, such as a module cover, covers the airbag. When a sensor detects a car crash, an inflator is activated, and generates gas (inflation gas) to inflate the airbag.
In Japanese Patent Publications (KOKAI) No. 01-247242 and No. 05-155300, a driver-side airbag having two compartments, namely a central compartment and a peripheral compartment, is disclosed. A partitioning panel divides inside of the airbag to form the two compartments, and the central compartment inflates first followed by the peripheral compartment. The partitioning panel has through ports or holes for the gas to flow out. The partitioning panel connects rear and front panels of the airbag to prevent the airbag from protruding forward when inflated.
Since the above-described airbag with the two compartments has a relatively large volume, the inflator, i.e. gas generator, is required to have a large capacity to inflate a peripheral portion of the airbag quickly, resulting in relatively poor gas efficiency.
An object of the present invention is to provide an airbag that improves the gas efficiency compared to the conventional airbag to protect a passenger even with a small capacity inflator.
Further objectives and advantages of the invention will be apparent from the following description of the invention.